Self-ignition internal-combustion engine



Nov. 3, 1953 F. G. GRAVES SELF-IGNITION INTERNAL-COMBUSTION ENGINE 2 Sheets-Sheet 1 Filed Oct. 6, 1948 INVENTOR.

FREDERICK G. GRAV E5 Nov. 3, 1953 GRAVES 2,657,677

SELF-IGNITION INTERNAL-COMBUSTION ENGINE Filed Oct. 6, 1948 2 Sheets-Sheet 2 INVENTOR. FREDERICK G. GRAVES Patented Nov. 3, 1953 SELF-IGNITION INTERNAL-COMBUSTION ENGINE Frederick G. graves, Parma, Ohio, assigncr to Justin W. hgaeklin Cleveland, Ohio, trustee Applicationflctober 6, 1948, Serial Nc. 53,103

7 Claims. (01. ce-cg) Th s i n n e ete f e n rna com ustio engines, asel-i i tedte e t sehh ti n typehei of t i cha act r t. has e n. nerally assumed to necessary, and cornmon oree ice. has been't t e c.c mp e s.ionv o the eihprier o i'el If ratios. oi fifteen to ei'gh. eon or mo n fa t the. modern tiiie'istowarasm11 higher compression ratigs in m s o. mprereeomhus n i the ue oil ccin only us egi.

ob ect. ofthepreeehtinven ntheref rais to prov de; a. p ans cyl er combus ion h mbe o g at mpl city un que coniormation il capebleo G at et deeir uhieh temperature iofr igniti n combustion of such. fuel oils, and which may operate most efficiently on com.- pression ratios of, sash. between nine, and eleven to one, 4

A Mo sp cific ohiect s toprvovide for. a sp al lation ip of; .cli 'c a e be ween thenieton and cylinder head at the moment of ignition, which will avoidiheim, pitz seme t of unburned afuel. a ainst the surfaces. and Whieh ill cause the. pr i ct onc t fu into a specially ereateii'hotezone of intensive air movement. t V o In carrying out myinventioniso arranged the surface formation oithepiston head and cylinder that on the stroke compressing the air a particue lar phenomenonof air. movementis set up whereby it forms. an annular zone (or ring) concentric with the axis of the piston, and in whichzone theairis caused to. recolve inpdirections such that art of the air is caused to whirl in'inwinding radial lanes. and. in. constantly narrowing nwintli e' Whirl aroundza ring-.iikeaxis. Thisring like axis .of whirlis concentric with the cylinder wall and thelongitndinal axis of the piston. n .Ohject is .to so shape the piston surface with relaticn to the inner. surface of the cylinder head that this spinning actionis commendedearly -in he compression stroke, and is continued-within reas d-intensity andzrapidity until the moment of greatest velocity of spin around this-annular axis is in; effectlat the :i-nneri ends of. the piston str Atithe en f the compressionstroke this 'spi ng ring of a1 id ay between the adjathe {intent As the ae heti mor tion ofv injection jets and.

clingler hea surface, and 11k tene esi Q1 .erdly the cen er of 0.1 intensify thespmnini'action to effectively cause 2 friction of the air. to increase the temperature aebdve h t al resu t n rom he compression. For convenience I refer to this spinning zone of air as a friction ring. In other Words, I create i t mper tu e fri on n of a and ent te nd. intensity s p nnin wh rl, atta nin tempera ur s at e cent or nnul r th uhi j en e n alcove he d bat c con..-

ecifi obiectsare to. so shape the outerr m oithe piston headsurface and. an, intermedi. ate zone. and the raised. center coneeshaped op 1': tru ca ed .siili h e. hereof that these surfaces contribute to the. increaseand maintenance of this spinning core. 0. friction ring of air, and that hehiehes poss le speed of spin may be ateaihe and. main ained. un il ignition, a d tinh e esezhe e tent o. as ur complete cmb tion.

. am. o Yar ou cone-shared. iete r se f-igni ion en i es of this n ture and of varions other shapes which include fortnhei e e'ih e n s 'e u e or: caviti n e.

d, anti of special cavities in the cyi cjlirider 1 inn r 'h etec i i u e .r ffl usually for the gene ii in the stirring 5a; W'ith the fuel' Inixtu-reat'the beginning of cointhe e 1T hustiom-an'ri to sortie e'zite'ntuntil combustion is" complete. It may be noted that in most of] these there is an eeeet; desireei by some} to delay igni tion. In the so-called inner cells'ot cavities out side the' cylinder chamber in which ignition or pre-ignition is effected, likewise-there'is a t1i1bli-' lence caused to' improve Imixt'urei and bu'rning'} An essentia1...diiierence in my invention over" such devices and special surfaceI'formations; is t at lam able to securev an i'gnition'temperatute oi the that an essential object of my invention is to atv nh ne ci cular core of the air, i...e.,;'the iii hen r n so o c rresooneto higher: 1 an ee h it may e ai amaze? tain efficient, uniform and complete combustion and instantaneous ignition in engines of this type while using a low overall compression ratio, such, for example, as about ten to one.

All conventional parts of such engines may be used with well-known fuel injection devices and equipment for a given horsepower. The cylinder, piston, connecting rods, crank, bearings, crank case, frame, etc., may all be of lighter weight and design, because of the greatly reduced impact and strain as compared with higher compression motors or engines of like nature.

Another advantage obtained by my invention is that my engine starts at the usual starting speeds and without the use of ignition devices, spark plugs, and the like. Somewhat higher, but still relatively low compression, self-ignition engines have special starting arrangements. For example, one well known engine running at just under twelve to one compression ratio utilizes a separate cavity which may be shut ofi, reducing the volume in the combustion chamber and increasing compression for starting purposes, Such a shut-off device, however, obviously adds expense and encounters trouble in maintenance, being subjected to the most severe temperatures and other damaging conditions. With my engine designed for approximately ten and one-half to one compression ratio, I have been able to start it readily after it had been idle in zero temperatures for a period of several days. The starting speed of turn-over of the crank shaft, in the instance given, was slightly above or about one hundred revolutions per minute.

In carrying out my invention I used a cylinder head which is sloped a few degrees. For example, seven degrees in a cone shape, and the rim of the piston and the height of the cylinder cone spreading surface at the center are so shaped as to attain the accomplished objects given above.

While my invention may be adapted to either two-cycle or four-cycle engines, in the embodiment shown, I have illustrated valves in the cylinder head, and the axis of these valves and their position in the head is such as to conform to the slope of the inner surface of the cylinder head.

As is well known, some two-cycle engines use a valve or valves in the head for certain functional of the piston part-way upon its compression stroke;

Fig. 3 is a similar section through the complete piston, on a somewhat enlarged scale;

Fig. 4 is a plan view of the top of the piston on the scale shown in Fig. 3;

Fig. 5 is a diagrammatic view showing the air movement near the upper end of the compression stroke of the piston;

Fig. 6 is a similar diagram illustrating the condition of the air at the top or inner end of the compression stroke, and at the time of firing; Fig. '7 is a diagrammatic view illustrating the 4 fuel jets projected radially into the inner spin ning zone of the air of the friction ring.

Describing the parts by the use of reference characters, I designates the inner cylinder wall, and 2 the water jacket of the cylinder onto which is fitted a cylinder head member 3 having a water jacket 4 and two valves designated 5. The top of the cylinder chamber forms a conical wall surface 6. l0 indicates the fuel injection nozzle holder having a nozzle H provided with jets from which the fuel is forcibly sprayed in a plurality of fan-like streams indicated at F, Figs. 6 and '7.

The piston, as shown, comprises essentially a skirt [5, wrist pin bosses l6 and an upper or inner end wall 20, of novel formation. The central portion of this top or inner wall of the piston comprises essentially a conical formation 20 merging with a horizontal or radial fiat portion 2i, while at the outer portion or periphery the wall slopes upwardly forming a rim 22-. A cross bracing rib or ribs, such as at 23, may be used to strengthen the head of the piston.

As stated for purposes of illustration, I have chosen a construction suited essentially to a four-cycle compression ignition engine. It will be understood that suitable mechanism may operate the inlet and exhaust valves 5 to admit air on a charging stroke and to effect the exhaust on the alternate stroke.

In attaining an effective increase of temperature, and the various other advantages outlined in the foregoing description, the particular shape and positioning of the various surface formations at the top of the piston coact with a slope of the cone-shaped inner surface of the cylinder head, and these surfaces and their relationships are critical.

The creation of turbulence during compression in engines heretofore known effects no appreciable increase in the temperature above the expected temperature which may be mathe-- matically arrived at as a result of the ratio ofv compression.

'As above indicated, I have discovered that with; certain shapes and relationships of surfaces at the head of the piston and the cylinder head, a phenomenon of very highly spinning air may be created, which, apparently, by reason of its. inwinding motion at extremely high speed, creates a zone of great friction, and probably for a brief instant, a localized zone of compression greater than that resulting from the com.- pression ratio alone. I

I am aware that cone shapes have been formed on the top of .the piston. I am familiar with the so-called energy cells in which the fuel is mixed with the airiby agitation and turbulence. I am familiar with step formations and various other attempts to increase efficiency of the fuel. burning. However, I believe that the phenomenon effecting quick and complete ignition as. well as attaining remarkably uniform mixturefor complete burning in a low compression engine is the result of my novel formations and? relationships at the piston and cylinder head.

As illustrated in the drawings, the cone-shaped.

portion 20 is preferably approximately one-half of the diameter of the piston, at its base, and rises to a height of one-quarter of its diameter above a flat portion 2|, which, in turn,.is below:

the raised rim 22.

The 'top of the cone portion 20 is preferably fiat, as indicated at 2%. The sloping top surface of the cone 7 is provided with concentric curved- 'is, the truncated surface, is about three-eighths of an inch from the cylinder surface. The fuel injection pressure may be lower than usual, but for ordinary purposes I use the conventional injection pumps capable of forcing the liquid fuel into the combustion chamber at two thousand to two thousand five hundred pounds, which being substantially lower than is customary, results in less wear on the injection system, and, incidentally, eifects saving of power to operate it.

The complete burning low compression factors contribute to more economical cooling in the water jacketed zone. In other words, we have .attained a higher thermal efiiciency and require less cooling for a given horsepower.

I claim:

1.. A cylinder with a nearly fiat conical head surface, and a piston with a cone and a surrounding flat surface and raised rim forming a chamher at the inner end of the compression stroke in which the walls are separated, and means for injecting radial streams of fuel at an angle midway between the cone surface on the piston and the slope of the conical surface of the cylinder head, whereby the fuel is ignited in a whirling ring of air, the cone having a flattened top surface of about one-seventh of the diameter of the piston, and the slope of the cone and the cylinder wall being divergent at an angle substantially twenty to twenty-five degrees.

2. A self-ignition engine adapted to start and run on compression ratios lower than 12 to 1, and having a piston and cylinder which form the complete combustion chamber and ignition means, the piston having its inner end provided with a central cone with a flattened area of approximately one-sixth of the diameter of the piston. and having a side wall formed generally on a thirty degree slope terminating at a substantially flat smooth radial surface extending from an inner edge of a diameter of about one-half the diameter of the piston, and having its outer edge about three-fourths the diameter of the piston, and meeting an upwardly sloping smooth surface extending at approximately thirty degrees to a narrow edge or rim at the perimeter of the inner face of the piston, the cylinder head surface comprising a fiat cone of seven to ten degrees, a fuel injection nozzle projecting therethrough at the center, the head surfaces and cylinder head defining the complete combustion chamber.

3. The engine defined in claim 2 in which inlet and exhaust valves are provided in the cylinder head and are each mounted to present their inner faces on a slope conforming to the slope of the cylinder head.

4. The engine described in claim 2 in which the nozzle directs a plurality of radial spray streams midway between the slope of said cone and the slope of the cylinder head, and in which the piston and cylinder surfaces cause the air being compressed to form an extremely high speed in- Jwinding friction air ring, the circular axis of which is about two-thirds or three-fourths the diameter of the piston.

5. The engine described in claim 2 in which the cone surface is provided with a series of annular concentric grooves each comprising approximately a one-fourth toroidal surface.

6. The structure described in claim 2 in which the cone surface ofthe piston is formed of three concentric stepped curves, the outer and lower edge of which is in a substantially radial plane, and each of the curved steps having a crosssectional extent of approximately one-fourth circle and .each of which projects a separate layer or stream of air toward an inwinding toroidal high pressure and high friction air ring.

'7. A self-ignition engine adapted to start and run on compression ratios of between 10 and 12 to 1, and without starting or firing aids, and having a piston and cylinder, a cylinder head having an inside surface extending in a uniform direction to the full diameter of the cylinder and on a slope less than ten degrees, inlet and exhaust valves in the cylinder head, a centrally positioned fuel injection nozzle for directing a plurality of radial streams of fuel at an angle slightly spaced from an inner head surface, the surfaces of the piston head being shaped to form a central cone having a base portion of slightly more than onehalf of the diameter of the piston and having side wall surfaces generally sloping at about thirty to forty degrees, the cone having a small portion at its apex omitted to shorten the cone in alignment with the injection nozzle and whereby the surface of the piston and cone are permitted to move into closer proximity, the side walls of said cone portion having formed thereon three or more concentric annular and outwardly curved trough-like baiile surfaces arranged in progressive steps from the top to the bottom of the cone, the piston having a substantially flat radial surface projecting outwardly from the cone and having an upwardly sloping uniform surface extending from the flat surface and rising about one-half the height of the cone and terminating near the periphery of the top of the piston, and the inner surface of the cylinder head and cylinder wall and piston head surfaces forming the complete combustion chamber, and whereby as the piston moves inwardly on the compression stroke, a plurality of layers of air are caused to whirl and form a rapidly spinning ring concentric with the piston and cylinder and into which ring the fuel streams are directed.

FREDERICK Gr. GRAVES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,001,358 Guernsey May 14., 1935 2,100,143 Mock Nov. 23, 1937 2,349,305 Pyk May 23, 1944 FOREIGN PATENTS Number Country Date 421,101 Great Britain Dec. 13, 1934 421,836 Great Britain Jan. 1, 1935 

